An optical parallel transmission system is expected to be widely applied to a computer interface, because the optical parallel transmission is advantageous in transmission speed, transmission distance, and anti-electromagnetic interference as compared to an electric parallel transmission system. In this optical parallel transmission system, an optical semiconductor module which is used for a light source of emitting light signals for an optical parallel transmission is required to be small in size and low in cost. For this purpose, optical semiconductor devices and optical fibers, etc. are desired to be arranged in array pattern for an optical parallel transmission.
A conventional optical semiconductor device array module used for such an optical parallel transmission comprises an LED (light emitting diode) array comprising a plurality of LEDs, an optical fiber array comprising a plurality of optical fibers, and a lens array for optical-coupling the optical fibers to the LEDs, respectively.
In operation, the LEDs are driven to emit light signals which are supplied through the lens array to input facets of the optical fibers, so that the light signals are transmitted in parallel through the optical fibers.
In the optical parallel transmission, the light signals tends to leak from one optical fiber to the adjacent optical fibers. One experiment shows that such leakage light resulting in cross-talk can be avoided to be less than 40 dB, when the adjacent optical fibers are separated in a distance between central axes thereof by more than 210 .mu.m, where an outer diameter of the optical fibers is 125 .mu.m (to be explained in detail later).
However, the conventional optical semiconductor device array module has a disadvantage in that it becomes large in size, especially, a width thereof becomes 1.39 mm, when six optical fibers each having an outer diameter of 125 .mu.m are arranged in array pattern with the aforementioned separated distance of 210 .mu.m (to be explained in detail later).
Accordingly, it is an object of the invention to provide an optical semiconductor device array module which is made small in size without occurrence of leakage light interface between adjacent optical fibers.
According to the invention, an optical semiconductor device array module, comprises:
a plurality of optical semiconductor devices arranged in array pattern with a predetermined interval or predetermined intervals in a direction perpendicular to light axes;
a plurality of lenses arranged in array pattern with the predetermined interval or intervals to focus lights emitted from the optical semiconductor devices on predetermined points;
a plurality of optical fibers arranged in array pattern with the predetermined interval or intervals to be positioned at the predetermined points by light input facets thereof and to be supplied with the lights focused by the lenses; and
a light shielding plate having a plurality of light apertures positioned to face the light input facets of the optical fibers;
wherein each of the light apertures of the light shielding plate has a predetermined radius, and a central axis common to a central axis of a core of each of the optical fibers.